I-alkoxy-z



Patented Oct. 21, 1947 I-ALKOXY-2,4-PENTADIENES AND SUBSTI- TUTED DERIVATIVES THEREOF Ewart Ray Herbert Jones, London, and John Talbot McCombie, Manchester, England, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application December 19, 1944, Se-

' rial No. 568,940. In Great Britain February 10,

4 Claims. (on. 260 614) 31 v This invention relates to a process for the manufacture of new unsaturated compounds and more particularly it relates to the manufacture of onn'=ca -ca=(on -cn='ca a to give dienols of the formula CRR' (OH) CR =CR -CH=CR R in both of which formulae R, R, R R R and R have the significance given above, by a process which comprises subjecting the first mentioned dienols to the action of an acidic substance oi the kind hereinafter described.

The starting-out materials of the formula given above may be obtained, when R is hydrogen. by

the partial hydrogenation of unsaturated i 1' 1- carbinols of the formula wherein R, R, R R and B have the $1 given above. Thus vinylethinylcarbinol CH2=CH.CH(OH) CECE may be hydrogenated to give divinylcarbinol CH2=CH.CH(OH) .CH=CH2 and propenylethinylcarbinol CHJCH=CH.CH(OH) .CECH

may be hydrogenated to give propenylvinylcarbinol, CH3CH=CH.CH(OH).CH=CHz; similarly z-methylpropenylethinyl carbinol (or, as it may also be named, 5-methylhexen-4-in-1-ol-8), (CH3)2C=CH.CH(OH).CECH, gives rise to 2- methylpropenylvinylcarbinol (or, as it may also be named, 5-methy1hexadien-1:4-01-3) (H3) 2C=CH.CH(OH) .CH=CHe 4-ethylocten-4-in-1-ol-3 crncincmcH=cEt.cH(on).cEcH

.- canoe 2 gives 4-ethyloctadien-1 :4-01-3 CHaCH2CHaCH=CEt.CH(OH) .CH=CH2 8-methylnonadien-2:7-in-4-ol-6 5 CHaCH=CI-I.CH(OH).CEC.CMe=CHCHa gives 3-methylnonatrien-2:4:7-01-6 CH3CH=CH.CH(OH) .CH==CH.CMe=CH.CHs octadien-1:6-in-3-ol-5 CI-Ia.CI-I=CH.CH(OH).C C.CH=CHQ gives octatrien-1:3:6-ol-5 CH:.CH=CH.CH(OH) .CH=CH.CH=C 2-methyloctadien-1:6-ln-3-ol-5 CHa.CH=CH.CH (OH) .CEC.CMG=CH2 gives 2-methyloctatrien-1z3; 6-01-5 CH3..CH(OH) .CH=CH.CMe==Cm 2 7-dimethyloctadien-1 6-in-3:pl-5

CI-Is.CMe--CH.CH(OH) .CEC.CMe'=CHz gives 2 'Zdimethyloctatrien-l :3 6-01-5- CHs.CMe=CH.CI-I(OH) .CH=CH.CMe=CHi z-methyl-fi-ethyldecadien-l:6-in-3-ol-5 CHzCHeCHaCH==CEiLCH(OH) .C-=-C.C'Me=CHa gives ?-methyl-6-ethyl-decatrien-l :3 6-01-5 omongomo eontomon .CH=OH.OMe=0Hn G-ethyldecemfi-in-B-ol-h CHaCH2CH2CH=CEt.CI-I(OH) .CECCHzCHa gives 6-ethyldecadien-3 6-01-5 QHsCHzCH=CEt.CI-I(OH).CH=CHCI-Ia and 3z5-dimethylhexen-4-in-1-ol-3 CEfiCMe 'CHCMdOH) CECH gives 3 :5=dimethy1hexadien-1 :4-01-3 CHsCMe=CI-I.CMe (OH) CH=CHz All these and other products are suitable for use in theprocess of the invention. The unsaturated ethinylcarbinols, from which the above dienols used in the process of the invention are obtained by partial hydrogenation, may themselves be obtained by known methods, that is to say by confor example acrolein, crotonaldehyde, 2-ethylhexen-2-al-1, z-methylcrotonaldehyde, or mesityl oxide, with alkali metal acetylides derived from, for example acetylene, ethylacetylene, vinylacetylene or 1:2-dimethy1vinylacetylene, under suitdensation of an unsaturated aldehyde or ketone,v

described for example in Nos. 2,125,384, 2,106,180,

2,106,181, and 2,106,182.

ere R is an alkyl radical the starting ma-' terials may not. of course be made by partial hydrogenation of an unsaturated ethinylcarbinol. However they can frequently be made by reduction of the corresponding ketone. Thus the dienol 2:8-dimethylheptadien-2z5-ol-4 CHICMFCHLCH(OH) .CH=CMeCH.1

may be made by reduction of phorone.

The acidic substances used in bringing about the isomerisation process of the invention are mineral acids for example boric acid, phosphoric acid, nitric acid, hydrochloric acid, and sulphuric acid, acid salts for example potassium hydrogen able conditions, is United States Patents sulphate, and organic acids, for example formic acid. acetic acid and tartaric acid. Also esterfying derivatives of these mineral or organic acids may be used, for example their anhydrides, for example acetic anhydride.

The reaction, when using the acids themselves, may conveniently be carried out in aqueous medium. An aqueous solution of the acidic substance may be used, of, for example, 25-25% strength, weight per volume, but more dilute or even stronger solutions may be used. The proces of the invention may conveniently be carried out for example by enclosing the dienol which it is desired to isomerise in a suitable vessel together with a substantial proportion of an aqueous solution of the acidic substance, the vessel being shaken or the contents stirred at, for example, atmospheric temperature, for a period which may vary from 3 to 100 hours or more or less according to the speed at which the reaction takes place. A solvent, for example ethanol, may be present if desired and this may be added in amount sufilcient to afford a homogeneous solution, in which case agitation may be omitted. The speed of isomerisation varies according to the particular acidic substance being used and also according to the strength of the solution of the acidic substance being used when working" of course desirable to avoid the presence of moisture. An anhydrous inert solvent may be used or a solvent may be dispensed with. Under these conditions the isomerised dienol is isolated in the form of its ester. Thus when using acetic anhydride it is isolated in the form of the acetate. Also when working in aqueous medium there is a tendency for the isomerised dienolto be partly or wholly converted to an ester by the isomerising acidic substance. Particularly is this the case when using certain acidic substances, for example hydrochloric acid. Esterification is favoured by high temperature and by high concentration of the acidic substance. Thus when using hydrochloric acid, if it is desired to avoid formation of the ester it is advisable to work with a dilute aqueous hydrochloric acid and at room temperature but using a stronger acid a good yield of ester may be obtained. When using sulphuric acid on the other hand isomerisation is not accompanied by appreciable esterflcation unless very high concentrations of acid are used.

Alternatively again the isomerisation may be carried out by using as acidic substance, for example concentrated sulphuric acid, in solution in an alcoholic solvent, for example methanol. ethanol or ethylene chlorohydrin. Under these conditions it is found that isomerisation is frequently accompanied by etheriilcation of the isomerised dienol in which case the product is isolated in the form of the ether.

The products obtained according to the invention are useful as intermediates in the manufacture of polymeric materials.

The invention is illustrated but not limited by the following examples in which parts. except where otherwise stated, are by weight:

trample 1 210 parts of propenylvinylcarbinol (hexadien- 1:4-01-3) are added to 550 parts of aqueous sulphuric acid (containing per parts by volume 1 part of sulphuric acid) in a vessel in which the air is replaced by nitrogen. The vessel is then shaken during 2 hours at 15--20 C. The contents of the vessel are then thoroughly extracted with ether. The ethereal extract is washed with water and with an aqueous solution of sodium bicarbonate until free from acid. It is then dried and distilled. There is thus obtained a colourlessliquid of B. P. 67-88 C./26 mms. and n l.48l0.' This is butadlenylmethylcarbinol (hexadien-1z3-ol-5). With. a-naphthyl isocyanate it gives an e-naphthylurethane M. P. 86.5-87.5 0.

Example 2 30 parts of propenylvinylcarbinol are added slowly to a cold solution of 1 part of concentrated sulphuric acid in 81 parts of methanol. The mixture is allowed to stand at 20 C. during 4 days. 500 parts of water are then added and the mixture is extracted with ether. The ethereal extract is washed until free from acid, dried and distilled. There is thus obtained a colourless liquid of B. P. 61-82 02/100 mms. and n 1.4488. This is 5-methcxyhexadiene-lz3.

Example 3 50 parts of propenylvinylcarbinol and 55 parts of acetic anhydride are mixed together and heated in an atmosphere of nitrogen on a steam-bath during 2 hours. Water is then added and when the acetic anhydride is completely hydrolysed the mixture is extracted with ether. The ethereal extract is washed with water and with aqueous sodium bicarbonate until free from acid and is then distilled. There is obtained a colourless liquid of B. P. 63-86 C./20 mms., and n 1.4583. This is 5-acetoxyhexadiene-1:3.

trample 4 116 parts or propenylvinylcarbinol are added slowly to a cold solution of 4 parts of concentrated sulphuric acid dissolved in v316 parts of absolute ethanol. The mixture-is allowed tostand for 20 hours at room temperature. 1500 parts of water are then added and the mixture is extracted with ether. The ethereal extract is washed with water until free from acid, dried and distilled. There is thus obtained a colourless, mobile liquid of B. P. 62.0-62.5 C./77 mms. and n -1.4484. This is 5-ethoxyhexadien-1z3.

Example 5 Example 6 A mixture of 11.7 parts of divinylcarbinol and 100 parts of aqueous sulphuric acid (containing per 100 parts by volume 1 part of sulphuric acid is agitated at 20 C. during 24 hours in an atmosphere of nitrogen. The product is then isolated by ethereal extraction as is described in Example 1 and is fractionally distilled. There is obtained a fraction after two distillations B. P. 95-97 C./100 mms., u 1.4902. This substance is pentadiene-2:4-ol-1. When reacted with anaphthylisocyanate it gives an a-naphthylurethane M. P. 97.5 C. and with maleic anhydride it gives an addition product M. P. HIE-176 C. When allowed to stand in air pentadiene-2z4-ol-1 changes slowly yielding a transparent polymeric substance.

Example 7 A mixture of 10 parts of isopropenylvinylcarbino], 100 parts of aqueous sulphuric acid (containing per 100 parts by volume 2 parts of sulphuric acid) and a trace of hydroquinone is agitated at C. during 24 hours in an atmosphere of nitrogen. Common salt is then added to the mixture until no more will dissolve. The product is then isolated by extraction with ether as is described in Example 1. There is obtained 2- methylpentadien-2z4-ol-1 as a colourless liquid B. P. 97-99 C./50 mms., 72-74 C./15 mms., 15, 1.5001. It gives with a-naphthylisocyanate an u-naphthylurethane M. P. 59-60 C. and with maleic anhydride an addition product M. P. 181-182" C.

Example 8 A mixture of parts of propenylvinylcarbinol, 124 arts of ethylene chlorohydrin and 1 part of concentrated sulphuric acid is stored at atmospheric temperature during 2-5 days. The product is then isolated as described in Example 1 and there is obtained after fractional distillation, 2-,6-chloroethoiqrhexadien-3:5, B. P. 79.5 C./7.5 mms., 15 1.4910. 4

We claim:

1. Process of preparing unsaturated ethers of the general formula.

wherein R stands for an alkyl grow containing up to 6 carbon atoms, R R, R. are each selected from the group consisting of hydrogen and alkyl groups containing up to 6 carbon atoms, and R is selected from the group consisting of hydrogen, the vinyl, methylvinyl and dimethylvinyl groups, which process comprises subjecting a compound of the general formula in which R, R, R, R and B. have' the same meaning as above, to the action of a mineral acid dissolved in an alcoholic solvent.

2. Process of preparing unsaturated ethers of the general formula wherein It stands for an alkyl group containing up to 6 carbon atoms. and R R, and R are each selected from the group consisting of hydrogen and alkyl groups containing up to 6 carbon atoms, which process comprises subjecting a compound of the general formula 'in which R 1K. and B have the same meaning as above, to the action of concentrated sulfuric acid dissolved in an alcoholic solvent.

3. Unsaturated ethers of the general iormula Aikoxy-CRR -CR"=CR -CH=CHR* wherein R stands for an alkyl group containing up to 6 carbon atoms, R R and R are each selected from the group consisting of hydrogen and alkyl groups containing up to 6 carbon atoms, and R is selected from the group consisting of hydrogen, the vinyl, methylvinyl 'and dimethyivinyl groups.

4. Unsaturated ethers of the general formula REFERENCES CITED The following references are of record the die of this patent:

UNITED STATES PATENTS Number Name Date 2,373,956 Hearne et a1. Apr. 1'1, 1945 2,207,070 Reppe et a]. July 9, 1940 2,344,085 Halbig et al. Mar. 14, 1944 OTHERREFIRENCES Delaby, Comptes Rendus de lAcedemie des Sciences, vol. 181 (1925). pp. 722-724. I

Prevost, Comptes Rendus de IAcedemie des Sciences, vol 184 (1927), p. 1562.

Young et al., Jour. Am. Chem. Soc.. vol. 61 

